x²-xy-6y²-2x+11y-3; 2x²-xy-6y²+3x+8y-2; 3x²+10xy-8y²-11x+26y-20; 要过

x²-xy-6y²-2x+11y-3; 2x²-xy-6y²+3x+8y-2; 3x²+10xy-8y²-11x+26y-20; 要过
x²-xy-6y²-2x+11y-3; 2x²-xy-6y²+3x+8y-2; 3x²+10xy-8y²-11x+26y-20; 要过

x²-xy-6y²-2x+11y-3; 2x²-xy-6y²+3x+8y-2; 3x²+10xy-8y²-11x+26y-20; 要过
用待定系数.
因为x²-xy-6y²=（x+2y)(x-3y),
设x²-xy-6y²-2x+11y-3=（x+2y+a)(x-3y+b)
=x²-xy-6y²+(a+b)x+(-3a+2b)y+ab.
比较系数得,a+b=-2,-3a+2b=11,ab=-3．解得a=-3,b=1．
所以 x²-xy-6y²-2x+11y-3=（x+2y-3)(x-3y+1)．
下面两题同样方法做．